The present invention relates to a method for fusion splicing optical fibers in a batchwise manner, and further relates to an apparatus for use in practicing the method. The batch fusion splicer is capable of performing batch fusion splicing in multimode for connecting multicore fibers, such as single, double, 4, 8, 10, and 12 core fibers.
The discharge power which is a heat source of splicing depends upon a variation in atmospheric pressure. The discharge power becomes smaller as the atmospheric pressure lowers at a constant discharge current. In an earlier attempt it has been proposed that: a variation in atmospheric pressure is detected and feedbacked to correct the discharge power according to the variation, so that the discharge current changes to produce a constant discharge power (see Japanese unexamined patent publication No. 63-106,706 and U.S. Pat. No. 5,122,638, for example).
The earlier attempt is briefly illustrated in FIG. 3, in which a voltage of a d.c. power source 10 is changed to a necessary high-frequency voltage through a dropper circuit 12, a chopper 14, and a step-up transformer 16, and thereby discharges take place at electrodes 18. The discharge current is detected by a resistance 20. The detected discharge current is feedbacked to the dropper circuit 12. These elements constitute a discharge control unit 22. In this attempt, an output of the pressure sensor 24 is provided to a microprocessor 26. The amount of feedback to the dropper circuit 12 is corrected in the microprocessor 26 on the basis of the output of the pressure sensor 24: when the atmospheric pressure becomes lower, the discharge power decreases, and therefore a correction is made to increase the discharge power.
In the prior art, the correction amount of the discharge power to a variation of atmospheric pressure cannot be, however, changed according to the number of fiber cores. When the correction amount is adjusted for 12 core fibers, for example, it is not appropriate for other fibers different in the number of cores. The correction amount can be excessively large for 4 core fibers.
Therefore, the correction amount is set to an intermediate value of the correction amounts of the all kinds of the fibers generally used. This setting is time consuming. Furthermore, the intermediate value does not produce sufficient results. More specifically, as illustrated in FIG. 4, the amount of correction for providing an appropriate discharge power is different for each number of cores, and in the case illustrated in FIG. 4 the amount of correction is set to that of the 8 core fibers which is intermediate. Considerable splice losses are produced for the other kinds of optical fibers.